This invention pertains to telecommunications, and more particularly, to the architecture and configuration of various nodes in a mobile communications network.
There is an ever increasing convergence of the media industry (including television, video, three dimensional graphics, electronic publishing, and entertainment), the computer industry (including desktop computer, personal computers connected by local area networks, electronic mail, Internet web sites, etc.), and the telecommunications industry (including both fixed and wireless communications networks). At the same time, the use of digital mobile communications devices is virtually exploding. The challenge for the next generation of mobile communications systems is the delivery of multimedia services.
Each one of these various industry services has its own bandwidth or data rate requirement. Voice, text, graphics, video, and Internet communications each have varying speed and other Quality of Service (QoS) requirements. Increasing numbers of subscribers along with the increased numbers of new services also increase bandwidth demands. At the same time, bandwidth is a limited resourcexe2x80x94particularly in the area of mobile radio communications.
Despite this limited radio bandwidth, there is increased pressure to meet the challenges of increased capacity, service offerings, and data rates in cellular mobile radio communications systems. The inventor of the present invention recognized that at least some of these challenges could be met by restructuring mobile communications networks using asynchronous transfer mode (ATM) technology. The inventor recognized in particular that different types of trafficxe2x80x94so-called multimedia trafficxe2x80x94could be better and more efficiently carried asynchronously rather than synchronously as in existing mobile communication systems. While the peak bandwidth requirement of multimedia traffic sources may be quite high, e.g., high resolution, full motion video, the duration for which that peak bandwidth is needed is relatively modest. In other words, while bursts of data ideally should be transmitted at the peak rate of the burst, the average arrival time between bursts may be quite large and randomly distributed. Conventional, hierarchical, and channelized multiplexing and switching architectures commonly used in mobile communications are designed primarily for voice services and do not efficiently support bursty, high bandwidth applications. Consequently, the inventors of the present invention recognized that a mobile communications network architecture based on asynchronous transfer mode multiplexing and switching would be better suited to handle bursty, multimedia traffic.
ATM utilizes xe2x80x9clabeledxe2x80x9d multiplexing and switching as opposed to xe2x80x9cpositionalxe2x80x9d multiplexing and switching in synchronous time division multiple access (TDMA) systems. Labeled multiplexing automatically adapts how much bandwidth is allocated to the size of the data block (referred to as a xe2x80x9ccellxe2x80x9d in ATM parlance) associated with each label. In addition, ATM is fundamentally a connection-oriented telecommunications approach which means that a connection is established between two stations before data is transferred between them. Because an ATM connection specifies the transmission path, ATM cells xe2x80x9cself-routexe2x80x9d through an ATM network. Another significant advantage of connection-oriented communication is that a guaranteed quality of service (QoS) may be guaranteed for each connection.
Therefore it is an object of the present invention to provide a mobile radio network communications architecture that efficiently handles multimedia communications services.
Mobile radio communication systems of the present invention include mobile radio units, radio base stations for communicating with the mobile radio units over a radio-based channel, and a radio switching station connected to the radio base stations for routing calls to and from various ones of the base stations. Each of the radio base stations and/or the radio switching station includes an asynchronous transfer mode (ATM) switch connected to plural function modules. Signaling and traffic communications between the function modules are effected asynchronously to efficiently and flexibly meet the current service bandwidth/data rate demands using the ATM switch and ATM switching protocols. Each function module includes a data processor and performs numerous ATM operations including cell buffering, for example. Each of the data processors communicates via the ATM switch using an ATM adaptation layer (AAL) protocol.
One or more of the function modules includes an extension module to permit communications with another ATM switch. The other ATM switch may be located, for example, at another base station. An ATM-based connection connects the two base stations in xe2x80x9ccascadexe2x80x9d via respective exchange terminal modules. In this fashion, additional base stations are easily added in modular fashion to increase the capacity of the radio communications network.
Capacity is also readily added to a base station or to a radio switching station as a result of the inventive architecture by modularly adding new function modules to vacant ports on the ATM switch. Existing function modules already connected to the ATM switch need not be modified or even taken off-line while new modules are added. This considerable flexibility and scalability allows fast and easy adaptation of the radio communications system to current demands. For example, a smaller radio communications network may start operation with a smaller number of function modules connected to each ATM switch node. As the network grows and expands, new nodes and/or function modules may be readily added to provide new services, service additional subscribers, etc. Additional modules may also include further extension modules as described above for cascading further base stations and/or radio switching stations. In even larger systems, one or more intermediate base station controllers may be added between the base stations and the radio switching station. The base station controller includes the similar architecture of an ATM switch connected to a plurality of function modules where communications between the function modules are effected using the ATM switch.
In a preferred embodiment, the radio mobile units and radio base stations communicate using a wideband, code division multiple access (CDMA) techniques. Wideband CDMA techniques further increase the capacity and flexibility of the radio communications network to deliver multimedia, broadband services.
These and other objects and advantages of the present invention are described more fully below in conjunction with the drawings and the detailed description of the invention.